Packer for wells

ABSTRACT

A well tool for controlling fluid flow through a well bore. It has particular application in the form of a packer or bridge plug for insertion down through a restriction such as tubing, collapsed casing or the like in a well and is adapted for expansion to a size sufficient to engage the casing at a point spaced below the restriction.

[4 1 Dec. 19,1972

United States Patent Woolley 1 PACKER FOR WELLS 1,734,040 1/1927 McEvoy 16.4 2,082,113 6/1937 Layne et a1. ....277/116.2 X

3/1956 Lynes 4/1958 Vincent..... 9/1950 Blood et al. .....l66/l96 X 5/1968 Crow et al. ....277/116.2 X 5/1958 4/1963 [22] Filed:

Lane ....277/116.2 ......277/116.2 X

Nielson et al.....

Related U.S. Application Data 4/1967 McCullough et al. ............166/192 X [63] Continuation-impart of Ser. No. 692,203, Dec. 20,

1967, abandoned.

Primary Examiner-David H. Brown Att0mey.1. Vincent Martin, Joe E. Edwards and Jack 52} U.S. c1. springgate 277/1 16.2 .E2lb 23/06, E21b 33/128, E2lb ABSTRACT A well tool for controlling fluid flow through a well [51] Int.

bore. It has particular application in the form of a packer or bridge plug for insertion down through a restriction such as tubing, collapsed casing or the like in a well and is adapted for expansion to a size suffim m 1 1 1 2 2 6 7l 3] l/ 4 32 m3 0 2 m6 9 l m2 9 .1 m2 8 6 A om d References Cited cient to engage the casing at a point spaced below the restriction.

UNITED STATES PATENTS 171,589 Stewart 16.8 22 Claims, 24 Drawing Figures PATENTED DEC 19 I972 SHEEI 3 OF 9 Woo/ y IWEWOR PATENTED DEC 19 I972 5/0W/7 J W00 //ey INVENTOR.

ATTORNEY PATENTED um 19 m2 SHEET 7 OF 9 PATENTEDIJEI: 19 I972 SHEEI 8 [IF 9 l I iZIV IZIZ IZ E Q I INVENTOR. ows W PACKER FOR WELLS This application is a continuation-in-part of my copending application, Ser. No. 692,203, filed Dec. 20, 1967, now abandoned.

This invention relates to a well tool for controlling fluid flow through a well casing at a point spaced below a restriction, such as a tubing, suspended in the casing. The tooltakes the form of a packer or bridge plug which is arranged for insertion down through the restriction. Itis arranged for expansion to a size sufficient to engage the wall of the casing below the restriction with a minimum of axial setting pressure.

There has heretofore been a serious problem in controlling fluid flow in a well, as for example, through a casing havinga tubing suspended therein. Heretofore, it has generally been necessaryto remove tubing in order to insert a bridge plug or packer into the casing. However, when it is not desirable or possible to remove the tubing or restriction from the casing, it is necessary to insert a packer therethrough. However, the tubing is of such smalldiameter, that it has been difficult to obtain a packer which would expand to the desired configuration to seal off the casing below the tubing without failure of the sealing element and within the limitation of conventional setting tool pressures. Hence, a need has existed for a tool which is not only of reduced size in diameter, so as to pass downwardly through the tubing, but which can be expanded with a minimum of force to the desired flow controlling position and which tool will operate uniformly and for extended periods of time without malfunctioning. Certain prior art apparatus use an inflatable-type'packer, but

they are subject to the limitation of controlling only relatively low differential pressures.

It is therefore an object of this invention to provide an improved well too] which will solve the foregoing problems and which tool can be set with a minimum of effort without the removal of tubing from the well bore.

Briefly stated, the tool of this invention comprises a body arranged for passage downwardly through a restriction in a well casing. It also includes a generally tubular mass of elastomeric material carried by the body and arranged for passage through the restriction and for axial compression and radial expansion to a diameter at least about twice the initial diameter. The apparatus also includes means movable relative to the body for axially compressing and radially expanding the mass of elastomeric material to a diameter of at least about twice the initial diameter thereof and into sealing engagement with the casing at a point spaced below the restriction.

It is a particular object of the invention to provide a packer element of elastic material which in its normal undistorted position is an elongate tubular body having a relatively thin wall; said element being so constructed that when endwise force is applied thereto the material of the element will overlap or telescope upon itself to form a plurality of overlying layers to thereby materially increase the outer diameter of the element, after which additional endwise force will deform the multiple layer packing element intoa final sealing position with a well casing or pipe.

Another object is to provide an improved pipe gripping assembly for locking the well packer in its sealing position, said assembly functioning to transmit forces created by the differential pressures across the packer element when said packer element is set, directly against said element, whereby the gripping means of said pipe gripping assembly is not subjected to excessive loads.

A further object is to provide an improved retaining means for confining the ends of the packer element, which retaining means is capable of being extended outwardly to relatively large diameters, whereby the packer element may be effectively set in larger size well casing and pipe.

Still another object is to provide an improved multiple spring assembly which is arranged in a relatively small diameter but which applies the necessary forces to maintain the tool in its set or locked position in the well pipe.

Reference to the drawings will further explain the invention wherein like numerals refer to like parts and in which:

FIG. 1 is a generally central vertical section of one presently preferred embodiment of the tool shown in the expanded fluid flow controlling condition in a well casing.

FIGS. 2A 2E comprise one complete figure, showing, generally in vertical central section and partially in side elevation view, the arrangement of the tool in the initial running in condition.

FIG. 3 is a cross sectional view taken generally at line 3--3 of FIG. 2C.

FIG. 4 is a cross-sectional view generally taken along line 44 of FIG. 2C.

FIG. 5 is an enlarged fragmentary view showing in greater detail the packing portion of the tool shown in FIG. 1.

FIG. 6 is a view generally taken along line 6-6 of FIG. 5,-with packer element 26 removed from the view.

FIG. 7 is a generally side elevation view of another alternate embodiment of the packing element of the tool.

FIG. 8 is also agenerally side elevation view of another alternate embodiment of the packing element of the tool.

FIG. 9 is a generally central vertical sectional view of a still further alternate embodiment of the packing element of the tool.

FIG. 10 is a cross-sectional view taken generally along line l010 of FIG. 2E.

FIG. 11 is an elevation of the preferred form of packer element showing the same in its normal undeformed position.

FIG. 12 is a vertical sectional view, which is somewhat enlarged over FIG. 11, illustrating the manner in which the packer element overlaps or telescopes upon itself to increase its diameter, said packer element being shown in a partially deformed position.

FIG. 13 is a longitudinal sectional view of a modified form of gripping means which may be utilized with the tool.

FIG. 14 is an enlarged view showing the gripping means of FIG. 13 in a set or gripping position.

FIG. 15 is a partial horizontal sectional view taken on the line 15-15 and illustrating the pivotal mounting of each gripping member.

FIG. 16 is an isometric view of one of the gripping members.

FIG. 17 is an elevation of the upper portion of the tool shown in FIG. 13, with the modified form of gripping means.

FIG. 17A is a continuation of the tool shown in FIG. 17.

FIG. 17B is a continuation of the tool shown in FIG. 17A and illustrating an improved type of multiple spring assembly which is utilized to maintain the tool in its set or locked position within the well pipe.

FIG. 18 is a vertical sectional view of a triple finger retaining assembly for use with larger diameter packers.

Referring now to FIG. 1, the tool is shown supported on wire line 11 which extends downwardly through a restriction in the form of tubing 12 suspended in well casing 13. It is to be understood that the tool in its initial condition is adapted for passage downwardly through the inside of tubing 12. Further, the tool is adapted for supporting by a wire line as well as by other tubing passed downwardly through tubing 12, for example. Wire line 11 has connected thereto a setting tool designated by the numeral 15 which may be of conventional design, but having a stroke of sufficient length to accomplish the desired setting which will be described hereinafter. A suitable tool can be that of a type manufactured and sold by Gearhart-Owen, Inc. of Fort Worth, Texas and shown in their catalog at page B-S-c and page B5d, dated Jan. I, 1966, modified to the extent of having the required length of stroke.

Further, the setting tool may be actuated either hydraulically, mechanically, or by an explosive charge. In the embodiment shown in FIG. 1, the setting tool includes a cylinder 16 with a piston 17 therein which-is connected to a piston rod 18 which in turn is connected by weakened point 19 to what has been described as the body of the tool in the form of mandrel 20. Piston 17 is arranged for actuation in the upward direction in response to an explosive charge in conventional manner. weakened point 19 is arranged for breaking at some load factor in excess of the load requirements for setting to tool of this invention so that the setting tool may be removed from the well bore.

Referring now to the tool of this invention, mandrel 20 is preferably hexagonal in outside configuration so as to provide indexing means for various components which are mounted thereon. It is to be understood that mandrel 20 may be either solid or hollow so that the tool may be used either as a bridge plug or a packer.

The tool includes locking means for locking the tool in the sealed position in the well, which locking means takes the form of snubber 22 mounted on mandrel 20. Immediately below snubber 22 is an upper slip assembly generally designated by the numeral 23 which is arranged for engaging the internal surface of casing 13 and securing the packer element to be described hereinafter against fluid pressure from below.

Below slip assembly 23 there is mountedan upper compensator spring designated by the numeral 24, the lower end of which engages upper container assembly designated by the numeral 25, which is arranged to engage and contain the upper end of the mass of elastomeric material which is to form the packer element generally designated by the numeral 26, and which also ismounted on mandrel 20.

The lower end of packer element 26 is adapted for engagement with and containment by lower container assembly 28'having a lower compensator spring 29 mounted therebelow and with lower slip assembly 30 mounted at the bottom end of the tool and supported on mandrel 20 by fastener nut 31.

Referring now to FIGS. 2A-2E, and starting at the top of the tool, setting tool 15 is shown having an explosive charge 35 which is adapted for actuation at a predetermined time and after thetool has been passed downwardly through tubing 12 by lowering on wire line 11. Snubber 22 includes tube 36 having a generally tapered internal bore in which is received a plurality of slip segments 38 having radially inwardly facing teeth which are arranged to engage and retain mandrel 20 in the set position of the tool. Segments 38 are held against upward movement during setting of the tool by means of a pair of O-rings 39 which are held in place by spring washer 34 and snap ring 40 mounted thereabove.

Upper slip assembly 23 includes a two stage expander cone generally designated by the numeral 41 and which may sometimes have to be referred to as one form of cam means for actuating the tool to the set position. Expander cone 41 includes member 42 having a depending flange portion in which is supported tubular rubber sleeve 43, the lower end of which abuts against ring 44. Member 42 is held against axial movement with respect to piston rod 18 by means of shear pin 45 passing transversely therethrough. The lower ends of member 42 and ring 44 are frusto conical in shape and together form a camming surface for engaging with and camming radially outward, the upper row of slips 48 of upper slip assembly 23. Further, the angle of the frusto conical portion on the lower end of ring 44 is less than the lower end of member 42. These features combine to facilitate initial outward camming of slips 48, with the final setting being effected by the lower ends of member 42 after shearing of pin 45.

Slips 48 are circumferentially spaced about mandrel 20 with the lower ends thereof pivotally connected to an annular spider 49 having an internal bore matching the external configuration of mandrel 20 and held thereto by shear pin 50. Slips 48 are resiliently biased inwardly by garter spring 51, which is held in recesses forming an annular groove thereabout.

The lower end of spider 49 abuts against another two-stage expander cone generally similar to expander cone 41 and having a member 52 with a depending flange and a ring 53 mounted therein. Member 52 is held on to mandrel 20 by shear pin 54 and the operation thereof is the same as two-stage expander cone 41. The lower ends of member 52 and ring 53 are arranged to engage and cam radially outwardly another circumferential row of slips 58, the lower ends of which are pivotally connected to another spider 59, which is generally similar to spider 49 and is held on mandrel 20 by shear pin 60. The lower end of spider 59 abuts against the upper end of upper compensator spring 24, which is mounted about mandrel 20, as shown.

Referring now to FIG. 2C, the lower end of spring 24 abuts against the upper container assembly 25 which includes another spider 63, having an axial bore therethrough of the same cross-sectional configuration as the external surface of mandrel 20 about which it is l060ll 0505 mounted to prevent rotation relative thereto. Spider 63 is held on mandrel 20 by means of shear pin 64 and has depending therefrom and pivotally attached thereto a circumferentially spaced apart row of fingers 65 which are retainingly held in the retracted position by garter spring 66 secured in recesses forming an annular groove thereabout. Each of the fingers 65 preferably have a plurality of teeth 67 on the radially inward side thereof and near the pivot end thereof, the purpose of which will be explained hereinafter.

Upon actuation of the tool to the set position, the lower ends of fingers 65 are adapted to be engaged and cammed radially outwardly by expander cone 71 which is held to mandrel 20 by shear pin 72. Cone 71 has depending therefrom and pivotally attached thereto another circumferentially spaced apart row of shorter fingers 75. Fingers 75 are resiliently retained in retractive position by garter springs 76 mounted in recesses forming an annular groove thereabout. The lower ends of fingers 75 are arranged to be engaged and extended radially outwardly by another expander cone 80 which is mounted on mandrel 20 and secured thereto by shear pin 81. It is to be understood that the fingers 75 are in staggered vertical alignment with fingers 65 and are arranged for intermeshing therewith upon actuation of the tool to the set position as shown in FIGS. 1 and 5, which staggered alignment is maintained by the indexing means in the form of the hexagon shape of mandrel 20 and the correspondingly shaped bores of spider 63 and cone 71. Additional rows of fingers may be provided if necessary to contain the packing element during axial compression thereof, if required,

In the expanded or set position of the tool, teeth 67 of fingers 65 are adapted to ride upon and be compressed into the frusto conical outside surface of expander cone 71 which preferably may be of somewhat softer metal or material.

The lower end of expander cone 80 is arranged to abut against the mass of elastomeric material which is to form the sealing engagement with the casing wall, and in the embodiment shown in FIGS. 2, 4 and 11 is a generally tubular packer element 26 of an elastomeric material such as rubber, neoprene, or the like, and is provided with a helical weakened zone, which weakened zone is in the form of helical Y shaped cut 86 which extends somewhat less than through the entire radial thickness thereof, but which does extend substantially from top to bottom thereof and helically thereabout. Further, and as shown in FIG. 4, helical cut 86 is preferably Y shaped, with the fork of the Y being at about the mid point of the thickness of the element, and the leg of the Y terminating short of the inside surface of the element.

Lower container assembly 28 is generally similar to upper container assembly 25 and includes the same parts in reverse vertical order. It includes an expander cone 80, fingers 75, expander cone 71, fingers 65 and spider 63, all of which are mounted on mandrel 20 in the same fashion as to upper container assembly 25.

Lower compensator spring 29, which is similar to V verted order and includes spider 59, slips 58, ring 53, member 52, spider 49, slips 48, ring 44 and member 42. The lower end of member 42 abuts against fastener nut 31 which is threaded to the lower end of mandrel 20.

In certain operations of the tool it is desirable that mandrel 20 be adapted for elongation under certain condition, as for example, the condition which might occur if alternate fluid pressures in opposite direction were applied on the tool. Means for accomplishing this elongation are provided in the form of a plurality of slots designated by the numeral 94 about the lower end thereof. Preferably there are three slots 94 spaced 120 apart centered in three flats of the hexagon mandrel 20, as best shown in FIG. 10. Depending upon the tensile strength of the material making up mandrel 20, it is desirable that the portion of mandrel 20 covered by slots 94 provide approximately 10% elongation of the slotted portion. The purpose of this elongation is to permit mandrel 20 to stretch rather than break, in order to allow slips 58 and 48 to set at one end of the tool after previous setting of the slips at the other end of the tool. It is to be understood that mandrel 20 in the area of slots 94 still has greater tensile strength than weak point 19 to permit setting of the tool.

. As shown in FIGS. 5 and 6, fingers 65 and at each end of packer element 26 interrnesh with each other and thereby confine packer element 26 during axial compression thereof. In addition, fingers 65 and 75 at each end of packer element 26 are adapted to axially compress and thereby radially expand packer element 26 upon actuation of the tool. In the actuated position, fingers 75 and 65 assume the intermeshing position best shown by FIG. 6.

In operation of the foregoing tool, it is initially assembled as shown in'FIG. 2A 2E, and thereafter run into the well casing through tubing 12 shown in FIG. 1. Thereafter, the setting tool 15 is actuated, which causes the upper end of snubber 22 to contact the lower end of cylinder 16 of the setting tool. The various shear pins, which have been described above, then shear in sequence top to bottom, such that the various parts of the tool are moved axially together and to the expanded position shown in FIG. 1, with slips 48 and 58 engaging the internal surface of casing 13, and with fingers 75 and 65 containing packer element 26.

The tool is particularly adapted for expanding packer element 26 to a diameter at least twice its initial diameter with a minimum of axial force. After setting of the tool as above described, thereafter wire line 11 may be raised, which thereby removes setting tool 15 and piston 18, which was previously sheared from mandrel 20 at shear point 19 during the setting of the tool.

Thereafter, if fluid pressure is applied below the tool, the slips of upper slip assembly 23 will be driven into deeper engagement with the wall of casing 13. If pressure is then applied to the upper end of the tool, the slips of lower slip assembly 30 will be more deeply engaged in the surface of casing 13 in a similar fashion. When this occurs, mandrel 20 is subjected to the additional elongation in the area of slots 94, whereby the slips of upper slip assembly 23 are still maintained in the deep embedded condition by upper compensator spring 24. The same function is performed by lower compensator spring 29 if pressure is once again reversed. Springs 24 and 29 may sometimes be referred to as biasing means.

l060l l 0506 Mandrel is locked in the locked position by slips segments 38 of snubber 22, and the tool can subsequently be removed from the well bore as by drilling, if it becomes desirable. Hence, the various components of the tool should preferably be of a drillable type material.

The tool of this invention is adapted to hold extreme pressure differentials on the order of 100,000 pounds end load, for example. Further, the tool is adapted for setting at a minimum of axial compression and well within the range of conventional setting tool which have setting pressures on the order of 13,000 psi. Moreover, the tool has a packer element which can be expanded into sealing pressures on the order of 13,000 psi. Moreover, the tool has a packer element which can be expanded into sealing engagement to an external diameter to at least about twice its original or initial diameter. Hence, it is readily adaptable for passage down through a restriction such as a tubing and for subsequent expansion for controlling fluid flow through a well bore casing below the lower end of the tubing suspended therein.

It has also been found that the particular configuration of element 26 is important in insuring that the packer element can be expanded to the desired diameter with a minimum of axial load. Element 26 is particularly adapted to this because of the helical weakened zone, which functions to cause the packer element 26 to rupture therealong, with the result that packer element 26 tends to spiral upon itself in movement to the expanded condition shown in FIG. 5. In other words, the weakened helical zone reduces the amount of axial pressure required to expand the packer element to the desired outside diameter, and to provide controlled rupturing or deformation thereof.

The manner in which the packer element 26 is deformed upon the application of endwise pressure is illustrated in FIGS. ll, 12 and 5. In FIG. 11, the packer element is shown in its normal undeformed condition and provides an elongate tubular body which will pass easily through a small size pipe, such as a 2 inch tubing string, The body of the packing element has a relatively thin wall thickness as compared to its length.

Upon the application of endwise force to the element 26, the initial application of pressure will rupture the weakened portions of the helical slot and will cause the sections of the packing element to overlap or spiral upon each other. Thus, as the packer element is foreshortened, its diameter is increased by reason of the overlapping action; this overlapping forms a packer element having multiple wall layers, such as indicated at 26, 26a, 26b, 26c and 26d in FIG. 12. After the packer element is converted into a multiple layer body a of greatly increased diameter, subsequent endwise force applied to said body moves the packer element into final sealing position, as is illustrated in FIG'. 5. When in such final sealing position, the various seams or contact areas between layers are firmly engaged with and merge into each other so that for all practical purposes the multiple layers disappear to form a relatively solid body of packing material which is confined between the containing fingers 65 and 75.

From the foregoing, it will be evident that a packing element which is initially a single wall body may be converted to a multiple layer wall packer by a relatively small amount of endwise force or pressure. By converting a single wall packer body into a multiple wall packer body, a rapid increase in diameter is effected, and this makes it possible to utilize the element to seal off within a relatively large casing. As an example, a packer body which will move downwardly through a 2 inch tubing when in its undeformed condition may be expanded outwardly into sealing engagement with a 7 inch well casing.

Alternate embodiments of the packer element are shown in FIGS. 7, 8 and 9, which are similarly arranged to expand to the desired diameter with a minimum of axial pressure applied thereto.

For example, FIG. 7 is a generally side elevation view of another packer element with a mass of elastomeric material in the form of a generally tubular rubber element 101 having a helical cut 102 therein which extends all the way through the thickness of element 101 and extends substantially from end to end thereof.

FIG. 8 shows another embodiment of a suitable packer element 103 having a plurality of lines or weakened zones 104 which are readily ruptured during expansion of the element to the setting or sealed condition. It is to be understood that element 103 could alternatively be composed of a plurality of rectangular squares of rubber or the like which are adhered together as by glue, but which nevertheless rupture along'the glue lines with a minimum of axial compression, but which do not disintegrate, and can be retained by the container means in the form of upper and lower container assemblies 25 and 28 in the expanded condition.

FIG. 9 shows a still further embodiment of a generally tubular shaped mass of elastomeric material including a plurality of discrete pieces 108 of rubber or the like enclosed within a membrane 109, whichis resilient enough to permit expansion thereof radially outward upon axial compression thereof. Membrane 109 serves to contain pieces 108 until container assemblies 25 and 28 have reached the expanded condition.

While the tool has been described as having two rows of fingers at each'end of packer element 26, it is to be understood that additional rows can .be provided to insure that the rubber of the packer element does not extrude therepast. In FIG. 18 is illustrated a triple finger assembly which may be employed, particularly with the larger diameter well casings. As shown in this figure, the spider 63 carries the finger 65, heretofore described, which is provided with the internal gripping teeth 67. In place of the cone 71, a similar expanding cone 171 is mounted upon the mandrel 20 and is adapted to expand the pivoted .fingers 65. Mounted upon this cone is an intermediate set of fingers 165 which are provided with inner teeth 167. The intermediate fingers 165 coact with and are adapted to be expanded by a second cone 271 which is also slideable with respect to the mandrel 20. The third set of fingers 265 are pivotally mounted on the cone which overlies the packing element 26. The cone 80 coacts with and expands the third set of fingers 265.

By reference to FIG. 18, it will be seen that when sufficient endwise force has been applied to the assembly to expand all of the fingers 65, and 265, the endwise pressure can thereafter be applied to the packing element 26. It is, of course, understood that the three sets of containing fingers are alternately arranged cir- I060ll 0507 cumferentially and when in an expanded position, provide an annular retaining or containing means which prevents an extrusion of the end of the packing element 26.

Similarly, the tool has been described as having two circumferential rows of slips at each end thereof arranged for engagement with the casing of the well. However, it is to be understood that fewer or more rows may be used at either end of the tool depending upon the direction and amount of force to which the tool will be subjected. Nevertheless, the operation of the tool is essentially the same.

It has also been found that when a packer element of the type heretofore described is used in combination with this tool, the loading required to expand the tool to the sealed condition is about one-fourth that required of solid-type packer elements having no such weakened zone or arrangement as discussed above.

The general specification of elastomeric packer element is that the material be 1500 psi to 4000 psi tensile at an elongation of 200 to 600 percent. When a onepiece element, such as packer element 26, having a dimension of 1% inch CD. by inch ID. by 36 inches axial length, is compressed endwise to 6 inches long, it is about 4 inches OD, and contained in a tube, and this is the practical limit of a material with a 500 percent elongation capability before it reaches its tensile strength in some portion of the distorted section. It has been found that the average end load required on a soft grade of neoprene where the element is not provided with a weakened zone, or otherwise arranged as taught herein, is about 700 psi which would be approximately 8500 pounds total endload in a 4 inch I.D. tube. This load is due to part of the element being stressed to its maximum extent, which requires a tensile strength in excess of 1500 psi.

It can be seen that if the element has the same volume in chunks and/or pieces which pieces can be controllably restacked or rearranged to conform to a new size cavity in which theyare thrust, end loading will be relatively small. After this rearranging of pieces of the element to generally conform to the cavity, the compression and expansion required to pack off and seal would be something less than 100 percent, rather than the 200 to 600 percent expansion and compression required of a solid type cylindrical element.

Since the percent of compression and elongation is thus greatly reduced, the corresponding load psi is greatly reduced and the total end load required to expand the element to seal-off or pack-off is greatly reduced by the same proportion.

The following chart showing the cross-sectional area of a solid element and of a packer element made in accordance with this invention, expanded to fit several pipe sizes, with corresponding psi and total end loading required for both, is as follows:

Solid Expanded area of packer element packer Pipe element cross end load element end load 1.D. section 700 P.S.l. 0150 P.S.l. 4" 12.2 sq. in. 8540 No. 1830 No.

5" 19.3 sq. in. (Uncontrolled rupture 2895 No.

6%" 31.6 sq. In. (Uncontrolled rupture 4740 No.

invention It will be noted that the solid element fails before sealing engagement is accomplished in the 5 inch l.D. pipe and larger because of the uncontrolled rupture, and hence, could not be used for the intended purpose. By contrast, the packer element made in accordance with this invention expands to all three sizes listed, and with much lower end load pressure.

In the form of the invention shown in FIGS. 1 6, the compensator springs 24 and 29 are disposed on each side of the container assemblies 26 and 28. This locates the springs between such assemblies and the gripping slip assemblies 23 and 30. With such location, a high pressure differential across the packing element 26,

[when the latter is in sealing position, may result in placing an excessive load upon one of the springs, which load is transmitted directly against the gripping slip members 48 and 58. An arrangement wherein the gripping slip members 48 and 58 can not be subjected to excessive loads, and also wherein the springs are protected, is illustrated in FIGS. 13 and 14.

As shown in these figures, the double slip expander 41 (FIG. 2A) is omitted and in place thereof, a slip expander 141 is mounted upon the mandrel 20. This expander is generally tubular and is formed of an upper sleeve portion 100, an intermediate flange 101, a lower expander portion 102 and an annular stop shoulder 103. The expander is connected to the mandrel by shear pin 104. A compensator spring 124 surrounds the mandrel and is confined between the snubber 22 and the upper end of the expander 141, functioning in a manner similar to the compensating spring 24 of the first form of the invention. A collar 105, angular in cross-section, encircles the flange 101 of the expander 141 and a spring 106 urges said collar into engagement with the upper surface of said flange portion; the upper end of the spring 106 is confined by a ring 107 secured to the upper portion of the sleeve of said expander.

The gripping slips 48 are pivoted within a spider 149 which is of a slightly different construction than the spider 49 of the first form. The bore 108 of the spider 149 has an internal shoulder 109 at its upper end and an inclined shoulder 110 at its lower portion. The spider is formed with a plurality of slots 14% (FIGS. 15 and 16) within which pivot pins 48a on the gripping slips 48 are engaged; the spider is formed with hook portions 1490 (FIGS. 13 and 14) which receive said pivot pins and thereby mount the slips for swinging movement.

Below the spider 149 is a second expander 141a which is identical in construction to the expander 141. Expander 141a includes the sleeve portion 100', the flange portion 101, the shoulder 103 and the beveled lower end 102; it is also connected by shear pin 104 to the mandrel and has a spring 106 urging a ring downwardly on the flange portion. The expander 141a coacts with the second set of gripping slips 58 which are pivoted to a spider 1490 having a construction identical to the spider 149. The spider 149a has the upper internal shoulder 109 and the lower beveled shoulder within its bore 108, and also has the hook portions 149a which receive the pivot pins of the gripping siips 58. A shear pin 150 connects the lower spider to the mandrel 20.

Below the gripping slip members 48 and 58 and their related parts as above described, are the containing fingers 65 and 75 which are pivoted, as has been l060ll 0508 described, on their respective support members 63 and 71. The packing element 26 is mounted in the same manner as heretofore described, and the lower gripping slip assembly will be the same as that shown and described, except that it will be in reverse since it is at the lower end of the tool. A lower compensator spring (not shown) similar to the spring 124 is provided below the lower gripping assembly.

In setting the tool, the mandrel is moved upwardly and the various shear pins will be progressively sheared to move the parts to the position shown in FIG. 14. Each set of gripping slips operate in the same manner and a description of the upper slips 48 will suffice. Initial upward movement of slips 48 cause the inclined lower end of expander 102 to move the slips outwardly, after which continued upward movement relative to the expander engages the slips with the lower edge of the ring 105; thering moves the slips outwardly into gripping engagement with the pipe casing.

As the slips move to fully set position, the ring 105 has moved upwardly on the flange 101 but is maintained in contact with the slips by the spring 106 so that the force of said spring urges the slips into gripping engagementwith the well pipe. At the same time, the lower end 102 of the expander has moved into engagement withthe shoulder 110 within the bore of the spider, with the shoulder 103 on the expander engaging the shoulder 109 within said bore; also, the underside of the flange 101 on the expander engages the hook portion 149a of the spider so that there is a direct engagement between the spider and the expander when the slips are in fully set position. This direct engagement transmits forces directly from the spider to the expander to thereby relieve the slips 48 of excessive loads. By selecting the strength of the spring 106, the force necessary to maintain the slips 48 in gripping position is provided.

The foregoing construction eliminates any excessive loads beingapplied to either the gripping members 48 or to the upper compensating spring 124. The lower set of slips 58 are actuated in exactly the same manner as are the upper slips and when in fully engaged position, any forces applied to the spider are transmitted directly to the expander and the gripping slips, and the compensator spring is notsubjected thereto.

In the larger size tools, the individual compensator springs, such as shown at 24 and 29 in FIG. 1, or as indicated at 124 in FIG. 13, may have to be of an excessive length in order to provide the forces required to perform the desired function of maintaining all parts in their locked position. In FIGS. 17, 17A and 173, there is shown a modified compensator spring assembly which is adapted to be mounted at the lower end of the tool. The particular tool shown in FIGS. 17 and 17A is the same as that illustrated in FIGS. 13 and 14, except that the compensator springs 124, which would be disposed at each end of the tool, have been omitted. The parts shown in FIGS. 17 and 17A comprise the upper gripping slips 48 and 58 with their coacting expanders 141 and 141a; the upper retaining fingers 65 and 75; the packer element 26; the lower retaining fingers 65 and 75; and the lower gripping slips 48 and 58.

The improved compensator spring assembly is illustrated in FIG. 17B and is mounted on the lower end of the tool. The mandrel 20 extends downwardly through an upper collar200 and sleeve 201 and is threaded into a connecting coupling 202. An intermediate mandrel 20a connects the coupling 202 with another coupling 203 and a lower mandrel 20b threaded into the lower end of the coupling 203 extends downwardly therefrom and has a nut 204 on its lower end.

The sleeve 201 has its lower end secured to a connecting collar 200a which, in turn, is connected to a second sleeve 201a; the latter has its lower end secured to a collar 200b. The sleeve assembly comprising the members 200, 201, 200a, 201a and 200b are all slideable with respect to the mandrels 20, 20a and 20b and with respect to their connecting couplings 202 and 203.

Confined within the upper sleeve member 201 and acting between the upper collar 200 and the upper end of the coupling 202 is a spring 205. This spring is generally circular in cross-secton but has one portion ground off to a flat surface as indicated at 205a. By so forming the spring, the spring may be of a maximum cross-sectional area while maintaining a minimum outer diameter of the spring coil; this provides for a spring of maximum strength within agiven diameter sleeve.

A second spring 206 of the same cross-sectional configuration, that having flat areas 206a, is confined within the sleeve portion 201a and acts between the lower end of the collar 200a and the coupling 203.'A third spring 207 extends between the bottom nut 204 and the underside of the connecting member 200b; because this spring need not be confined within a sleeve, it may be of circular cross-section but if desired it may have the same cross-sectional shape as springs 205 and 206.

The action of the springs 205, 206 and 207 is such that their forces are additive to constantly urge the mandrel 20 in a downward direction while urging the outer sleeve members upwardly. The uppermost collar 200 engages the lower end of the tool and functions to apply an upward force to those members which will effect a setting of the gripping slips and an expansion of the container fingers. When the mandrel is moved upwardly to effect a setting of the tool, the forces of all three springs will be acting to maintain the tool in its set position. Because it is desirable to maintain the outer diameter as small as possible, the particular configuration of the springs 205 and 206 provide springs of maximum strength while maintaining a minimum outer diameter of the spring coils. The compensator shown in FIG. 178 may be used in place of the springs 24 and 29 of the first form of the invention shown in FIG.1 and would connect to the lower end of the tool between nut 31, shown in FIG. 1, and thelower gripping slip assembly 30.

Further modifications may be made in the invention, as described, without departing from the scope thereof. Accordingly, the foregoing description is to be construed as illustratively only and not as a limitation upon the invention as defined in the following claims:

What is claimed is:

1. In a well tool for controlling fluid flow through a casing at a down hole location, the combination comprising:

a body member arranged for passage downwardly in said casing;

a generally tubular mass of elastomeric material carried by said body member and arranged for passage downwardly in said casing in the relaxed condition and for substantial radial expansion at a predetermined time;

at least two circumferential rows of fingers mounted on said body member at each end of said mass of elastomeric material, with the fingers of oneof the rows on one end of said mass being in staggered vertical alignment with the fingers of the other row adjacent thereto,

each of said fingers of each row on each end of said mass being pivotally supported at only one end thereof, with the free end of each finger being adapted upon expansion of said tool to engage the inner wall of said casing and with the fingers in one row arranged to intermesh with the fingers in the adjacent row;

cam means at both ends of said mass for camming said fingers radially outward upon actuation thereof;

and means operably connected to said body member for actuating said cam means to thereby extend said fingers and for effecting relative axial movement of said rows of fingers on one end of said mass toward the rows of fingers on the other end of said mass to thereby axially compress and radially outwardly expand said mass.

2. The invention as claimed in claim 1 including;

retainer means operably connected to said mass for securing said mass in a down hole location.

3. The invention as claimed in claim 2 including:

biasing means operably connected between said retainer means and the fingers at one end of said mass for exerting a biasing force urging said retainer means and said fingers axially apart to thereby maintain said fingers and said retainer means in the engaged position.

4. The invention as claimed in claim 2 wherein:

said retainer means includes a plurality of slips axially spaced apart from each end of said mass and arranged for activation to the set position engaging said casing as an incident of expansion of said mass.

5. The invention as claimed in claim 4 wherein:

the slips at one end of said packer are arranged to provide greater resistance to axial force in the direction from said mass than the slips at the other end of said mass provide to force in the opposite direction.

6. The invention as claimed in claim 4 wherein:

said slips are mounted in circumferential rows about said tool, with each row being supported by spider mounted on said body.

7. In a well tool for controlling fluid flow through a casing, the combination comprising:

a body member arranged for passage through said casing;

a packing element having an annular layer of elastomeric material in generally tubular form mounted upon said body member, said layer having a substantially continuous helical weakened zone extending substantially from end to end thereof and arranged for parting along said weakened zone and conversion to a plurality of layers upon application of axial compression to the ends thereof to thereby increase the outer diameter thereof;

and means cooperative with said body member for axially compressing said element to thereby part said layer along said weakened zone and to convert said element into a plurality of layers sealingly engaging said casing.

8. The invention as claimed in claim 7 wherein:

said weakened zone in said tubular member is in the form of a helical Y-shaped cut.

9. The invention as claimed in claim 7 wherein:

said helical weakened zone is in the form of a helical cut.

10. In a well tool for controlling fluid flow through a casing in a well bore, the combination comprising:

a body member arranged for passage through said casing;

a packing element having a single annular layer of elastomeric material in generally tubular form mounted upon said body member for passage downwardly through said casing in the relaxed condition, said layer having a single substantially continuous helical weakened zone extending substantially from end to end thereof whereby upon axial compression said layer parts along said weakened zone and sections of said layer spiral one upon another to thereby increase the outer diameter of said element;

and means cooperative with and supported by said body member for applying said compression to said element to thereby expand said element into sealing engagement with said casing.

11. In a well tool for controlling fluid flow through a casing at a down hole location, the combination comprising:

a body member arranged for passage downwardly in said casing;

a generally tubular mass of eleastomeric material carried by said body member and arranged for passage downwardly in said casing in the relaxed condition and for substantial radial expansion at a predetermined time;

at least two circumferential rows of fingers mounted on said body memberat each end of said mass of elastomeric material, with the fingers of one of the rows on one end of said mass being in staggered vertical alignment with the fingers of the other row adjacent thereto;

cam means at both ends of said mass for camming said fingers radially outward upon actuation thereof;

means operably connected to said body member for actuating said cam means to thereby extend said fingers and for effecting relative axial movement of said rows of fingers on one end of said mass toward the rows of fingers on the other end of said mass to thereby axially compress and radially outwardly expand said mass;

each row of said fingers being mounted on a spider member carried by said body member;

and said body member including index means for holding said spider members against rotation therewith.

12. The invention as claimed in claim 11 wherein:

each of said cam means includes a generally conical expander cone;

and at least one row of said fingers is provided with teeth for engaging the expander cone adjacent thereto upon actuation of said mass to the expanded condition.

13. The invention as claimed in claim 1 1 including:

locking means associated with said body for locking said mass in the expanded position. i

14. The invention as claimed in claim 1 1 wherein:

said tubular mass of elastomeric material is provided with a substantially continuous helical weakened zone extending substantially from end to end thereof and arranged for parting along said weakened zone and conversion to a plurality of layers upon application of axial compression to the ends thereof to thereby increase the outer diameter thereof.

15. In a well tool for controlling fluid flow through a casing at a down hole location, the combination comprising:

a body member arranged for passage downwardly in said casing;

a generally tubular mass of elastomeric material carried by said body member and arranged for passage downwardly in said casing in the relaxed condition and for substantial radial expansion at a predetermined time;

at least two circumferential rows of fingers mounted on said body member at each end of said mass of elastomeric material, with the fingers of one of the rows on one end of said mass being in staggered vertical alignment with the fingers of the other row adjacent thereto;

cam means at both ends of said mass for camming said fingers radially outward upon actuation thereof;

means operably connected to said body member for actuating said cam means to thereby extend said fingers and for effecting relative axial movement of said rows of fingers on one end of said mass toward the rows of fingers on the other end of said mass to thereby axially compress and radially outwardly expand said mass;

resilient means mounted on said body to exert a force against the expanded mass of elastomeric material in a direction to maintain said mass in such expanded position;

sets of locking slips mounted on the body above and below the rows of fingers for locking the tool within a well pipe;

and spring means independent of the resilient means acting upon each set of locking slips to hold the same in locking engagement with said well pipe.

16. In a well tool for controlling fluid flow through a casing, the combination comprising:

a body member arranged for passage through said casing;

a packer element of elastomeric material mounted upon said body member;

said element being generally tubular and having a relatively thin annular wall'as compared to its length when said element is in a normal undeformed condition;

the material of said element consisting of portions which are displaceable radially outwardly and axially to assume an overlapping relationship to other portions thereof when an axial compressive force is applied to the ends of the element, whereby the external diameter of the element is substantially increased;

said displaceable portions of the material of said element comprisinga plurality of elastomeric block like segments which are formed by partially slitting the material of the packing element;

and means cooperative with said body member for axially compressing said packer element to effect displacement of said portions and to deform the element into sealing engagement with said casing.

17. In a well tool for controlling fluid flow through a casing, the combination comprising:

a body member arranged for passage through said casing;

a packer element of elastomeric material mounted upon said body member;

said element being generally tubular and having a relatively thin annular wall as compared to its length when said element is in a normal undeformed condition;

the material of said element consisting of portions which are displaceable radially outwardly and axially to assume an overlapping relationship to other portions thereof when an axial compressive force is applied to the ends of the element, whereby the external diameter of the element is substantially increased;

said displaceable portions of the material of said element comprising a plurality of elastomeric members which are contained within an outer flexible membrane forming a container for said members.

18. In a well tool for controlling fluid flow through a casing at a down hole location, the combination comprising:

a body member arranged for passage downwardly in said casing;

a generally tubular mass of elastomeric material carried by said body member and arranged for passage downwardly in said casing in the relaxed condition and for substantial radial expansion at a predetermined time;

at least two circumferential rows of fingers mounted on said body member at each end of said mass of elastomeric material, with the fingers of one of the rows on one end of said mass being in staggered vertical alignment with the fingers of the other row adjacent thereto;

cam means at both ends of said mass for camming said fingers radially outward upon actuation thereof;

means operably connected to said body member for actuating said cam means to thereby extend said fingers and for efiecting relative axial movement of said rows of fingers on one end of said mass toward the rows of fingers on the other end of said mass to thereby axially compress and radially outwardly expand said mass;

spring compensator means mounted on the body member and exerting forces in a direction to maintain the fingers extended and the mass of l060ll OSll mandrel which is secured to the lower end of the body member and which has extemai abutments thereon; i

and a plurality of springs disposed around the mandrel and confined between the external abutments on said mandrel and the internal abutments on said casing, whereby said springs exert their forces to urge the mandrel and the sleeve-like casing in opposite axial directions.

19. A well tool as set forth in claim 18 wherein:

each spring which is confined within the casing is formed of a material which is initially circular in cross-section but is truncated to provide a flat side, whereby said spring is of maximum cross-sectional area for a predetermined diameter of spring coil.

20. In a well tool for controlling fluid flow through a casing, the combination comprising:

a body member arranged for passage through said casing;

a packer element of elastomeric material mounted upon said body member;

said element being generally tubular and having a relatively thin annular wall as compared to its length, said element having no portion of its wall overlapping any other portion of its wall when said element is in a normal undeformed condition;

means responsive to the application of an axial force to the ends of said element foreshortening the element;

the annular wall of said element being sufficiently thin relative to the annular space between said element and the casing so that upon foreshortening of the element portions of said element are moved into an overlapping relationship in both longitudinal and radial directions with respect to other portions of the element, said overlapping portions forming multiple layers which increase the effective wall thickness of the packer element to thereby substantially increase the external diameter of said packer element;

and means cooperative with said body member for axially compressing said packer element to effect said overlapping and to move the element into sealing engagement with said casing.

21. A well tool as set-forth in claim 20 wherein:

the means responsive to the application of an axial force comprises a helical slit formed in the packer element which slit extends longitudinally from end to end of the element and also extends completely through the wall of the element in a transverse direction.

22. In a well too] for controlling fluid flow through casing, the combination comprising:

a body member arranged for passage through said casing;

a packer element of elastomeric material mounted upon said body member;

said element being generally tubular and having a relatively thin annular wall as compared to its length, said element having no portion of its wall overlapping any other portion of its wall when said element is in a normal undeformed condition; the material of said element consisting of portions which are displaceable both radially outwardly and longitudinally of each other to assume an overlapping relationship to other portions thereof to form multiple layers which increase the effective wall thickness of the packer element when an axial compressive force is applied to the ends of the element, whereby the external diameter of the element is substantially increased; and means cooperative with said body member for axially compressing said packer element to effect displacement of said portions and to deform the element into sealing engagement with said casing.

l060ll 0512 

1. In a well tool for controlling fluid flow through a casing at a down hole location, the combination comprising: a body member arranged for passage downwardly in said casing; a generally tubular mass of elastomeric material carried by said body member and arranged for passage downwardly in said casing in the relaxed condition and for substantial radial expansion at a predetermined time; at least two circumferential rows of fingers mounted on said body member at each end of said mass of elastomeric material, with the fingers of one of the rows on one end of said mass being in staggered vertical alignment with the fingers of the other row adjacent thereto, each of said fingers of each row on each end of said mass being pivotally supported at only one end thereof, with the free end of each finger being adapted upon expansion of said tool to engage the inner wall of said casing and with the fingers in one row arranged to intermesh with the fingers in the adjacent row; cam means at both ends of said mass for camming said fingers radially outward upon actuation thereof; and means operably connected to said body member for actuating said cam means to thereby extend said fingers and for effecting relative axial movement of said rows of fingers on one end of said mass toward the rows of fingers on the other end of said mass to thereby axially compress and radially outwardly expand said mass.
 2. The invention as claimed in claim 1 including; retainer means operably connected to said mass for securing said mass in a down hole location.
 3. The invention as claimed in claim 2 including: biasing means operably connected between said retainer means and the fingers at one end of said mass for exerting a biasing force urging said retainer means and said fingers axially apart to thereby maintain said fingers and said retainer means in the engaged position.
 4. The invention as claimed in claim 2 wherein: said retainer means includes a plurality of slips axially spaced apart from each end of said mass and arranged for activation to the set position engaging said casing as an incident of expansion of said mass.
 5. The invention as claimed in claim 4 wherein: the slips at one end of said packer are arranged to provide greater resistance to axial force in the direction from said mass than the slips at the other end of said mass provide to force in the opposite direction.
 6. The invention as claimed in claim 4 wherein: said slips are mounted in circumferential rows about said tool, with each row being supported by a spider mounted on said body.
 7. In a well tool for controlling fluid flow through a casing, the combination comprising: a body member arranged for passage through said casing; a packing element having an annular layer of elastomeric material in generally tubular form mounted upon said body member, said layer having a substantially continuous helical weakened zone extending substantially from end to end thereof and arranged for parting along said weakened zone and conversion to a plurality of layers upon application of axial compression to the ends thereof to thereby increase the outer diameter thereof; and means cooperative with said body member for axially compressing said element to thereby part said layer along said weakened zone and to convert said element into a plurality of layers sealingly engaging said casing.
 8. The invention as claimed in claim 7 wherein: said weakened zone in said tubular member is in the form of a helical Y-shaped cut.
 9. The invention as claimed in claim 7 wherein: said helical weakened zone is in the form of a helical cut.
 10. In a well tool for controlling fluid flow through a casing in a well bore, the combination comprising: a body member arranged for passage through said casing; a packing element having a single annular layer of elastomeric material in generally tubular form mounted upon said body member for passage downwardly through said casing in the relaxed condition, said layer having a single substantially continuous helical weakened zone extending substantially from end to end thereof whereby upon axial compression said layer parts along said weakened zone and sections of said layer spiral one upon another to thereby increase the outer diameter of said element; and means cooperative with and supported by said body member for applying said compression to said element to thereby expand said element into sealing engagement with said casing.
 11. In a well tool for controlling fluid flow through a casing at a down hole location, the combination comprising: a body member arranged for passage downwardly in said casing; a generally tubular mass of eleastomeric material carried by said body member and arranged for passage downwardly in said casing in the relaxed condition and for substantial radial expansion at a predetermined time; at least two circumferential rows of fingers mounted on said body member at each end of said mass of elastomeric material, with the fingers of one of the rows on one end of said mass being in staggered vertical alignment with the fingers of the other row adjacent thereto; cam means at both ends of said mass for camming said fingers radially outward upon actuation thereof; means operably connected to said body member for actuating said cam means to thereby extend said fingers and for effecting relative axial movement of said rows of fingers on one end of said mass toward the rows of fingers on the other end of said mass to thereby axially compress and radially outwardly expand said mass; each row of said fingers being mounted on a spider member carried by said body member; and said body member including index means for holding said spider members against rotation therewith.
 12. The invention as claimed in claim 11 wherein: each of said cam means includes a generally conical expander cone; and at least one row of said fingers is provided with teeth for engaging the expander cone adjacent thereto upon actuation of said mass to the expanded condition.
 13. The invention as claimed in claim 11 including: locking means associated with said body for locking said mass in the expanded position.
 14. The invention as claimed in claim 11 wherein: said tubular mass of elastomeric material is provided with a substantially continuous helical weakeneD zone extending substantially from end to end thereof and arranged for parting along said weakened zone and conversion to a plurality of layers upon application of axial compression to the ends thereof to thereby increase the outer diameter thereof.
 15. In a well tool for controlling fluid flow through a casing at a down hole location, the combination comprising: a body member arranged for passage downwardly in said casing; a generally tubular mass of elastomeric material carried by said body member and arranged for passage downwardly in said casing in the relaxed condition and for substantial radial expansion at a predetermined time; at least two circumferential rows of fingers mounted on said body member at each end of said mass of elastomeric material, with the fingers of one of the rows on one end of said mass being in staggered vertical alignment with the fingers of the other row adjacent thereto; cam means at both ends of said mass for camming said fingers radially outward upon actuation thereof; means operably connected to said body member for actuating said cam means to thereby extend said fingers and for effecting relative axial movement of said rows of fingers on one end of said mass toward the rows of fingers on the other end of said mass to thereby axially compress and radially outwardly expand said mass; resilient means mounted on said body to exert a force against the expanded mass of elastomeric material in a direction to maintain said mass in such expanded position; sets of locking slips mounted on the body above and below the rows of fingers for locking the tool within a well pipe; and spring means independent of the resilient means acting upon each set of locking slips to hold the same in locking engagement with said well pipe.
 16. In a well tool for controlling fluid flow through a casing, the combination comprising: a body member arranged for passage through said casing; a packer element of elastomeric material mounted upon said body member; said element being generally tubular and having a relatively thin annular wall as compared to its length when said element is in a normal undeformed condition; the material of said element consisting of portions which are displaceable radially outwardly and axially to assume an overlapping relationship to other portions thereof when an axial compressive force is applied to the ends of the element, whereby the external diameter of the element is substantially increased; said displaceable portions of the material of said element comprising a plurality of elastomeric block-like segments which are formed by partially slitting the material of the packing element; and means cooperative with said body member for axially compressing said packer element to effect displacement of said portions and to deform the element into sealing engagement with said casing.
 17. In a well tool for controlling fluid flow through a casing, the combination comprising: a body member arranged for passage through said casing; a packer element of elastomeric material mounted upon said body member; said element being generally tubular and having a relatively thin annular wall as compared to its length when said element is in a normal undeformed condition; the material of said element consisting of portions which are displaceable radially outwardly and axially to assume an overlapping relationship to other portions thereof when an axial compressive force is applied to the ends of the element, whereby the external diameter of the element is substantially increased; said displaceable portions of the material of said element comprising a plurality of elastomeric members which are contained within an outer flexible membrane forming a container for said members.
 18. In a well tool for controlling fluid flow through a casing at a down hole location, the combination comprising: a body member arranged for passage downwardly in said casing; a generally tubular mass of elastomeric material carried by said body member and arranged for passage downwardly in said casing in the relaxed condition and for substantial radial expansion at a predetermined time; at least two circumferential rows of fingers mounted on said body member at each end of said mass of elastomeric material, with the fingers of one of the rows on one end of said mass being in staggered vertical alignment with the fingers of the other row adjacent thereto; cam means at both ends of said mass for camming said fingers radially outward upon actuation thereof; means operably connected to said body member for actuating said cam means to thereby extend said fingers and for effecting relative axial movement of said rows of fingers on one end of said mass toward the rows of fingers on the other end of said mass to thereby axially compress and radially outwardly expand said mass; spring compensator means mounted on the body member and exerting forces in a direction to maintain the fingers extended and the mass of elastomeric material in outwardly expanded position; said spring compensator means including a central mandrel which is secured to the lower end of the body member and which has external abutments thereon; and a plurality of springs disposed around the mandrel and confined between the external abutments on said mandrel and the internal abutments on said casing, whereby said springs exert their forces to urge the mandrel and the sleeve-like casing in opposite axial directions.
 19. A well tool as set forth in claim 18 wherein: each spring which is confined within the casing is formed of a material which is initially circular in cross-section but is truncated to provide a flat side, whereby said spring is of maximum cross-sectional area for a predetermined diameter of spring coil.
 20. In a well tool for controlling fluid flow through a casing, the combination comprising: a body member arranged for passage through said casing; a packer element of elastomeric material mounted upon said body member; said element being generally tubular and having a relatively thin annular wall as compared to its length, said element having no portion of its wall overlapping any other portion of its wall when said element is in a normal undeformed condition; means responsive to the application of an axial force to the ends of said element foreshortening the element; the annular wall of said element being sufficiently thin relative to the annular space between said element and the casing so that upon foreshortening of the element portions of said element are moved into an overlapping relationship in both longitudinal and radial directions with respect to other portions of the element, said overlapping portions forming multiple layers which increase the effective wall thickness of the packer element to thereby substantially increase the external diameter of said packer element; and means cooperative with said body member for axially compressing said packer element to effect said overlapping and to move the element into sealing engagement with said casing.
 21. A well tool as set forth in claim 20 wherein: the means responsive to the application of an axial force comprises a helical slit formed in the packer element which slit extends longitudinally from end to end of the element and also extends completely through the wall of the element in a transverse direction.
 22. In a well tool for controlling fluid flow through a casing, the combination comprising: a body member arranged for passage through said casing; a packer element of elastomeric material mounted upon said body member; said element being generally tubular and having a relatively thin annular wall as compared to its length, said element having no portion of its wall overlapping any other portion of its wall when said element is in a normal undeformed condition; the material of said element consisting of portions which are displaceable both radially outwardly and longitudinally of each other to assume an overlapping relationship to other portions thereof to form multiple layers which increase the effective wall thickness of the packer element when an axial compressive force is applied to the ends of the element, whereby the external diameter of the element is substantially increased; and means cooperative with said body member for axially compressing said packer element to effect displacement of said portions and to deform the element into sealing engagement with said casing. 